\DOC MATCH_ACCEPT_TAC
\TYPE {MATCH_ACCEPT_TAC : thm_tactic}
\SYNOPSIS
Solves a goal which is an instance of the supplied theorem.
\KEYWORDS
tactic.
\DESCRIBE
When given a theorem {A' |- t} and a goal {A ?- t'} where {t} can be
matched
to {t'} by instantiating variables which are either free or
universally quantified at the outer level, including appropriate type
instantiation, {MATCH_ACCEPT_TAC} completely solves the goal.
{
A ?- t'
========= MATCH_ACCEPT_TAC (A' |- t)
}
Unless {A'} is a subset of {A}, this is an invalid tactic.
\FAILURE
Fails unless the theorem has a conclusion which is instantiable to match
that
of the goal.
\EXAMPLE
The following example shows variable and type instantiation at work. We
can use
the polymorphic list theorem {HD}:
{
HD = |- !h t. HD(CONS h t) = h
}
to solve the goal:
{
?- HD [1;2] = 1
}
simply by:
{
MATCH_ACCEPT_TAC HD
}
\SEEALSO
Tactic.ACCEPT_TAC.
\ENDDOC